The invention relates to a ventilation device. Ventilation devices of the type according to the invention serve for ventilating and venting spaces inside housings of electrical control devices, especially for automotive applications.
One ventilation device is disclosed in German Utility Model G 91 15 939.3 U. That ventilation device has a connecting piece integrally bonded to the housing by frictional welding in a receiving opening in a wall of an electrical device housing. A pressure-compensating element, which includes a carrier plate, an outer plate, and a membrane located between the plates and which is joined together in one piece by ultrasonic welding, is fixed in the connecting piece by frictional welding. The pressure-compensating element is protected, especially against mechanical damage, by a cover fitted on the connecting piece. The cover has openings, through which a gas can flow, to the region of the membrane. The ventilation device is complicated in construction and complex to produce.
International PCT publication WO 96/03629 discloses a ventilation device with a protective membrane for a silicon pressure sensor. In the device, a hollow space and a membrane are provided above a silicon chip to be protected and ventilated. An annular covering fixes the membrane. The annular covering is resilient, especially to compensate for temperature fluctuations. The ventilation device is also complicated in its construction and is expensive to produce.
It is accordingly an object of the invention to provide a ventilation device that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that can be produced in a simple and cost-effective manner.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a ventilation device including a wall having at least one inner opening open to an inner space of the wall for receiving and delivering gas from and to the inner space, at least one outer opening open to the surroundings for receiving and delivering gas from and to the surrounding, the at least one inner opening and the at least one outer opening laterally offset to not overlap, a ventilation duct unit fluidically connecting the at least one inner opening to the at least one outer opening for leading the gas between the at least one inner opening and the at least one outer opening, and a membrane unit disposed in the ventilation duct unit.
The invention has the advantage that spray water directed onto the housing from outside can at most penetrate the outer duct opening, but generally cannot penetrate the inner opening. Such is true because the two openings are not disposed in line. Consequently, water must first penetrate the ventilation duct unit. Penetration is difficult because the ventilation duct unit, which is disposed in the wall of the housing, extends essentially perpendicular to the spray water impingement direction.
In accordance with another feature of the invention, there is provided a covering layer bonded to the wall.
In accordance with a further feature of the invention, the ventilation duct unit includes a depression disposed in the wall surrounding the inner opening, and includes at least one ventilation duct formed as a recess in the wall, fluidically connected to the depression, and extending away from the depression.
In accordance with an added feature of the invention, the covering layer covers the inner opening, the recess, and at least part of the ventilation duct.
In accordance with an additional feature of the invention, the covering layer does not cover an end of the ventilation duct.
In accordance with yet another feature of the invention, the at least one outer opening is an end of the ventilation duct remote from the depression and is not covered by the covering layer.
In accordance with yet a further feature of the invention, the membrane unit has a gas-permeable membrane, and the gas-permeable membrane has at least one property selected from the group consisting of hydrophobic and oliophobic.
In accordance with yet an added feature of the invention, the covering layer is one of the group consisting of a company plate, a type identification plate, and a print carrier. It is particularly advantageous that type identification plates, which are typically fitted on electrical devices, at the same time form a wall of the ventilation duct unit. Membranes can be inserted and exchange in a simple manner because they are merely attached adhesively into a depression, which presents no problems before fitting the type identification.
In accordance with yet an additional feature of the invention, the outer opening is disposed at a level lower than the membrane unit.
In accordance with again another feature of the invention, the ventilation duct is at least two ventilation ducts extending outward essentially radially from the inner opening and essentially perpendicularly to each other.
The ventilation duct device may advantageously be configured such that the outer duct openings are disposed in the direction of gravity below the membrane, so that spray water that has entered is led to the outer duct openings under the effect of gravity.
In accordance with again a further feature of the invention, the depression has a base surface and the membrane unit is adhesively bonded to the base surface.
In accordance with again another feature of the invention, the wall is a housing.
In accordance with a concomitant feature of the invention, the ventilation device is for an electrical control device.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a ventilation device, especially for electrical control devices, it is nevertheless not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.